How do mobile siRNAs mediate transgressive methylation in grapevine plants?

Grapevine (Vitis vinifera) is a major fruit crop worldwide whose development and productivity are strongly affected by the choice of rootstock. Transcriptomic studies have shown that the rootstock can modify scion gene expression. Grafting has also been shown to affect miRNA abundance, with variations between hetero- and autografted grapevines. The impact of the rootstock on scion gene expression and miRNA abundance suggests that some smRNAs can move across the graft union and may thus be responsible for changes in scion phenotypes. However, the transgressive methylation mediated by mobile siRNAs in grapevine plants has not previously been investigated.

Recently, scientists from University Bordeaux analyzed the populations of smRNAs in homo- and heterografts, taking advantage of sequence differences in the genomes of the heterograft partners to analyze the possible exchange of smRNAs. They demonstrated that the type of grafting per se dramatically influenced the smRNA populations, independent of genotype, but there were also genotype-specific effects. The researchers demonstrated that bilateral exchange of smRNAs, mainly short interfering RNAs, may occur in heterografts, with preferential transfer of smRNAs from the scion to the rootstock.

“We have developed a bioinformatic approach based on the sequence differences between the genomes of scion and rootstock to demonstrate a bi-directional small RNA transfers between graft partners that may lead to changes in DNA methylation profiles,” Prof. Gallusci said. These results suggested that smRNAs may have an important role in the phenotype modifications observed in heterografts.

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Reference

Authors

Bernadette Rubio, Linda Stammitti, Sarah Jane Cookson, Emeline Teyssier and Philippe Gallusci*

Affiliations

EGFV , University Bordeaux, Bordeaux Sciences Agro, INRAE, ISVV , F-33882, Villenave d’Ornon, France

About Dr. Philippe Gallusci

The long-term goal of Prof. Philippe Gallusci’s research is to understand the role of epigenetic control in plant and fruit development, with a focus on DNA methylation and polycomb proteins. His main interest is epigenetic control of fruit quality in grape and tomato, and his research has analyzed the contribution of epigenetic mechanisms to the control of grafting and hence to cell dedifferentiation and differentiation processes. His team is also interested in the inheritance of epigenetic variation and its role in shaping phenotypic diversity in plants, particularly clonally propagated plants.